Bash / Sed, <strike>705</strike> 668 chars
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A pretty simple solution, based on the significant repetition in the song.<br>
Line breaks within the `sed` command are not needed, characters are counted without them.

    sed "
    s/L/ MWe'veKn each other for so longMYour heart's been aching butMYou're too shy to say itMInside we bothK what's been going onMWeK the game+we'reZplay itM/;
    s/T/MI just wanna tellU how I'm feelingMGotta makeU understandR/;
    s/R/M ~giveU up~letU down~run around+desertU~makeU cry~say goodbye~tell a lie+hurtU/g;
    s/E/(Ooh)~give, neverZgiveM(GV/g;
    s/V/iveU up)M/g;
    s/U/ you/g;
    s/+/ and /g;
    s/K/ know/g;
    s/~/MNeverZ/g;
    s/Z/ gonna /g;
    s/M/\n/g
    "<<Q
    We're no strangers to love
    YouK the rules+so do I
    A full commitment's what I'm thinking of
    You wouldn't get this from any other guyT
    LAnd ifU ask me how I'm feeling
    Don't tell meU're too blind to seeRR
     
    (Ooh, gV(Ooh, gVEEL TRR
    Q